1. Field of the Invention
The present invention relates to a process for the preparation of isoparaffins having 4 to 7 carbon atoms per molecule from synthesis gas including the following steps:
a) synthesizing a heavy paraffins-containing hydrocarbon mixture over a Fischer-Tropsch catalyst; PA1 b) converting at least part of the heavy paraffins-containing hydrocarbon mixture over a bi-functional isomerization/hydrocracking catalyst under isomerization/hydrocracking conditions; PA1 c) separating the normal paraffins from at least part of the isoparaffins-containing product of step (b); and PA1 d) recycling at least part of the normal paraffins to step (b) and withdrawing the C.sub.4 -C.sub.7 isoparaffins as a product. PA1 a) synthesizing a heavy paraffins-containing hydrocarbon mixture over a Fischer-Tropsch catalyst; PA1 b) converting at least part of the heavy paraffins-containing hydrocarbon mixture over a bi-functional isomerization/hydrocracking catalyst under isomerization/hydrocracking conditions; PA1 c) separating normal paraffins from at least part of the isoparaffins-containing product of step (b); and PA1 d) recycling at least part of the normal paraffins to step (b) and withdrawing C.sub.4 -C.sub.7 isoparaffins as a product from the process.
2. Description of the Prior Art
In certain instances, it is desirable to produce a specific type of hydrocarbon because of its benefit in preparing a particular product. A number of different reactions for producing hydrocarbons have been practiced over the years. Fischer-tropsch synthesis, the contacting of a mixture of carbon monoxide and hydrogen with a suitable catalyst at an elevated temperature and pressure, is a well-known process for the production of various types of hydrocarbons. Only a small amount of iso-paraffins, a specific type of hydrocarbon which are of particular importance in preparing such products as gasolines and fuels, are produced utilizing the Fischer-Tropsch synthesis.
It has now been found that iso-paraffins may be produced in an efficient manner utilizing the process of the present invention.